Method for obtaining location information for emergency services in wireless multimedia networks

ABSTRACT

In accordance with the teachings of the present invention, a method and apparatus for obtaining end-user location information for emergency services within a multimedia network is presented. The multimedia network may include a network implementing the Session Initiation Protocol, H.323, etc. In one embodiment, a Location Application Server (LAS) in the multimedia network and an interface between the LAS and a gateway mobile location center (GMLC) is defined.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to communications. Specifically, communication ofan emergency request.

2. Description of the Prior Art

Communications networks are becoming ubiquitous. The lines that oncedifferentiated voice networks, data networks and video networks areblurring. In addition, wireless networks and terrestrial networks suchas circuit-switched networks and packet-switched networks are oftenintegrated.

Currently there are substantial wireless networks in North America,Europe, Asia and other parts of the world. These wireless networks areoften based on communications standards. For example, Second-GenerationWireless Network (2G) standards and Third-Generation Wireless Network(3G) standards are currently being deployed. Some of the more recentstandards provide for multimedia traffic such as voice and data trafficacross these networks.

Circuit-switched and packet-switched networks have also advanced toprovide more capability and functionality such as multimediafunctionality. In addition, standards based protocols such as H.323 andSession Initiation Protocol (SIP) are currently being deployed tointegrate multimedia functionality across terrestrial networks, such aspacket-switched networks.

Given the need for ubiquitous communications, methods have developed forproviding multi-media capability across wireless, packet-switched andcircuit-switched networks. In order to properly integrate the networks,the services offered in any aspect of the network must be properlymanaged in other parts of the network. Some services currently beingoffered in the circuit-switched and packet-switched network also need tobe supported in the multimedia network.

One specific service that is currently offered in wireless networks isan emergency service. The emergency service enables the ability toobtain the location of a wireless end user device and provide thatlocation to the emergency service provider. Thus, there is a need for amethod and apparatus for obtaining location information for emergencyservices within a multimedia network.

SUMMARY OF THE INVENTION

A method and apparatus is presented that obtains wireless end-userlocation information for emergency services within a multimedia network.In one embodiment, end-user location information is obtained within amultimedia network at session initiation. In a second embodiment, enduser location information is obtained within a multimedia network aftersession initiation. In order to accomplish the foregoing methods, in oneembodiment of the present invention, an application server, such as aLocation Application Server (LAS) is implemented in a multimedianetwork. In accordance with the teachings of the present invention, aninterface (i.e., herein referred to as an M1 interface) is defined toenable communication between the LAS and a Gateway Mobile LocationCenter (GMLC).

In accordance with the teaching of the present invention, a multimediaarchitecture is defined. In one embodiment, the multimedia architectureincludes user equipment (UE), a Proxy-CSCF (P-CSCF), a Server-CSCF(S-CSCF), a LAS and a GMLC. Two methods of operating the multimediaarchitecture are defined. In one embodiment, location information isacquired at session initiation. In a second embodiment, locationinformation is acquired after session initiation.

At session initiation, a UE sends an emergency request (e.g., INVITE) toa P-CSCF. The P-CSCF forwards the emergency request to a S-CSCF. Onreceipt of an emergency request (e.g., INVITE) the S-CSCF forwards therequest to the LAS. The LAS sends a location request to the GMLC via anM1 interface. The GMLC initiates a Mobile Terminating Location Request(MT-LR) procedure to determine the UE's location information. Thelocation information is returned to the LAS and then to the S-CSCF. TheS-CSCF includes the location information in the emergency request (e.g.,INVITE) and communicates the emergency request (e.g., INVITE message) toan EC.

After session initiation, a UE sends an emergency request (e.g., INVITE)to a P-CSCF. The P-CSCF forwards the emergency request to a S-CSCF. Onreceipt of an emergency request (e.g., INVITE) the S-CSCF forwards therequest to the LAS. The LAS sends a request for routing information tothe GMLC via an M1 interface. The GMLC sends an acknowledgementincluding routing information that will enable the EC to request the UElocation at a later time (e.g. a routing key). At any time afterreceiving the request for routing information, the GMLC initiates aMobile Terminating Location Request (MT-LR) procedure to determine theUE's location information. Upon receipt of the emergency request (e.g.,INVITE message), the EC can request location information from the GMLCby using the routing information obtained in the emergency request(e.g., INVITE message).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 displays a wireless IP multimedia (IMS) network implementing theteachings of the present invention.

FIG. 2 displays a network implementing the method of acquiring locationinformation at session initiation.

FIG. 3 displays a message flow diagram depicting a method of acquiringlocation information at session initiation.

FIG. 4 displays a network implementing the method of acquiring locationinformation after session initiation.

FIG. 5 displays a message flow diagram depicting a method of acquiringlocation information at session initiation.

DESCRIPTION OF THE INVENTION

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the invention is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, and embodimentswithin the scope thereof and additional fields in which the presentinvention would be of significant utility.

In one embodiment of the present invention, a multimedia network isdefined. The multimedia network includes a Location Application Server(LAS). In one embodiment, the LAS is an implementation of an ApplicationServer specifically for location services. In accordance with theteachings of the present invention, a communication interface, referredto as an M1 interface is defined between the LAS and a Gateway MobileLocation Center (GMLC). The M1 interface enables communication betweenthe LAS and the GMLC. As such, location information associated with UserEquipment (UE) may be communicated to an Emergency Center (EC) using themultimedia network. In one embodiment, the GMLC provides thefunctionality required to support location services and is positioned ina location services network.

The method and apparatus of the present invention are in compliance andmay implement various features and concepts from 3GPP TS 23.002; 3GPP TS23.060; 3GPP TS 23.228; 3GPP TS23.003; and 3GPP TS 23.271, which areeach herein incorporated by reference. It should be appreciated thatwhile specific references have been identified, the invention is notlimited to the cited references.

A multimedia network architecture is defined. In one embodiment, themultimedia network architecture operates using the Session InitiationProtocol (SIP) as defined in Internet Engineering Task Force (IETF) RFC3261 (June 2002), which is herein incorporated by reference. However, itshould be appreciated that the multimedia network architecture may beimplemented with a variety of competing technologies such as H.323 asdefined in the International Telecommunications Union (ITU), version 7,approved Jul. 7, 2003. In one embodiment, the multimedia networkarchitecture includes a Call Session Control Function (CSCF) andApplication Server (AS). The CSCF may be implemented as a Proxy-CSCF(P-CSCF) and/or a Server-CSCF (S-CSCF). The P-CSCF communicatesinformation from the UE to the S-CSCF. The S-CSCF communicates with theEC and with the AS.

In accordance with the teachings of the present invention, a method andapparatus is implemented for obtaining a wireless end user's locationinformation for emergency services within a multimedia network. ALocation Application Server (LAS) is implemented in the multimedianetwork. In accordance with the teaching of the present invention, an M1interface is defined between the LAS and a GMLC to obtain the wirelessend user's location information in the multimedia network. The M1interface enables communication between the LAS and GMLC. In oneembodiment, multimedia protocols such as Session Initiation Protocol(SIP) and H.323 are implemented in the multimedia network to facilitateacquisition of the wireless end user's location information. In oneembodiment, the location information is obtained at session initiation.In a second embodiment, the location information is obtained aftersession initiation. Each method may be initiated based on when thelocation information is requested.

FIG. 1 displays a communication network implemented in accordance withthe teachings of the present invention. In FIG. 1 User Equipment (UE) isshown as 102. In one embodiment, UE 102 is implemented to detect anemergency service request and to indicate the emergency service requestto a network. The UE 102 communicates with access networks 101 as wellas an multimedia network 105. For example, the UE 102 communicates witha GSM Edge Radio Access Network (GERAN) 112 and a Universal TerrestrialRadio Access Network (UTRAN) 122. In one embodiment, the GERAN 112, andthe UTRAN 122 are implemented as access subsystems to access a corenetwork 103.

The GERAN 112 communicates through core network 105 using aSecond-Generation Message Switching Center (2G-MSC) 114 and/or aSecond-Generation Serving GPRS Support Node (2G-SGSN) to a GatewayMobile Location Center (GMLC) 120. The UTRAN 122 communicates throughcore network 105 using a Third-Generation Serving GPRS Support Node(3G-SGSN) 124 and/or a MSC server 126 to the GMLC.

In accordance with the teachings of the present invention, the UE 102 iscapable of communication with an multimedia network 105. In oneembodiment, the multimedia network 105 is implemented as an IPMultimedia Core Network Subsystem (IMS) network compliant with 3GPP TS23.228 v6.5.0 (2004-03), which is herein incorporated by reference. Inone embodiment of the present invention the IMS network 105 includes aProxy CSCF (P-CSCF), Serving CSCF (S-CSCF) and Location ApplicationServer (LAS) 116.

In FIG. 1, the UE 102 communicates with a P-CSCF 104, which communicateswith a S-CSCF 106. The S-CSCF 106 communicates with a LocationApplication Server (LAS) 116. The LAS 116 communicates across an M1interface with a GMLC 120. In one embodiment, the P-CSCF 104 functionsas a proxy by accepting request, services the request and/or forwardsthe request for servicing. The P-CSCF 104 may function as a user agentterminating and independently generating transactions such as SIPtransactions. In one embodiment, the S-CSCF 106 manages session statesas necessary to support services operating in the network. In oneembodiment, the LAS 116 receives emergency session establishment requestfrom the S-CSCF 106, sends location and routing information request tothe GMLC 120 and on receipt of location and/or routing information, theLAS 116 forwards the location and/or routing information to the S-CSCF106. The S-CSCF 106 then forwards the location and/or routinginformation to the EC 108. In the scenario where routing information isforwarded to the EC 108, the EC 108 may the access the GMLC 120 toaccess the location information.

FIG. 2 displays a network implementing a method of obtaining locationinformation at session initiation. A UE 202 communicates with a P-CSCF204. The P-CSCF 204 is capable of communication with an S-CSCF 206. TheS-SCSF 206 communicates with the EC 208 and the LAS 212. In accordancewith the teachings of the present invention, the LAS 212 is capable ofcommunication with the GMLC 214 using a defined M1 interface. The GMLC214 is ultimately in communication with the serving nodes(MSC/SGSN/SMLC) 216.

During operation, an INVITE request 203 is sent from the UE 202 to theP-CSCF 204. The P-CSCF 204 detects that the user is initiating anemergency call and forwards the INVITE request 205 to a S-CSCF 206 inthe same network 210. In accordance with the teachings of the presentinvention, the S-CSCF 206 detects this is an emergency call and forwardsthe INVITE request 218 to the LAS 212. A Location Request 220 is sentfrom the LAS 212 to a GMLC in the same network 214. In one embodiment,the location request 220 may be an immediate location request or adeferred location request.

The GMLC 214 sends a Location Service (LCS) Mobile Terminal LocationRequest (MT-LR) 222 to the server nodes 216. In one embodiment, theMT-LR procedures are implemented in accordance with the MT-LR proceduresdescribed in 3GPP TS 23.271 V6.7.0 (2004-03), which is hereinincorporated by reference. The server nodes 216 communicate a responseincluding the location information of the user to the GMLC 224 (as shownby the two-directional arrow 222). The GMLC 214 communicates a LocationResponse 326 including the location information of the user to the LAS212. The LAS 212 communicates an INVITE message 224 including thereceived location information of the user to the S-CSCF 206. The S-CSCF206 then forwards the INVITE message 207 including the locationinformation of the user to the EC 208.

FIG. 3 displays a message flow diagram depicting a method of acquiringlocation information at session initiation. The message flow diagram ofFIG. 3 depicts message flow between S-CSCF 300, LAS 302, GMLC 304 and EC306. During operation, a SIP INVITE request 310 is communicated from theS-CSCF 300 to the LAS 302. The LAS 302 sends a location request 312 tothe GMLC 304. In one embodiment, the GMLC 304 is pre-configured andresides in the same network (e.g., home or visited network 308) as theLAS 304. In one embodiment, the location request includes the type oflocation (e.g., current location), the UE's public identity and therequired quality of service (QoS), such as the accuracy, response time,etc.

Upon receipt of the Location Request 312, the GMLC 304 initiates MobileTerminating Location Request (MT-LR) procedures as shown by 314 toobtain the UE's location. In one embodiment, the MT-LR procedures areimplemented in accordance with the MT-LR procedures described in 3GPP TS23.271 V6.7.0 (2004-03). The GMLC 304 returns the location informationto the LAS 302 in a Location Response 316. The LAS 302 then includes thelocation information in a SIP INVITE request 318 to the S-CSCF 300. Avariety of packet formats and messages may be used to implement theforegoing methods. For example, the Internet Protocol or the GSM MAPprotocol may be used.

FIG. 4 displays a network implementing the method of acquiring locationinformation after session initiation. A UE 402 communicates with aP-CSCF 404. The P-CSCF 404 is capable of communication with an S-CSCF406. The S-CSCF 406 may communicate with the EC 408 and the LAS 412. Inaccordance with the teachings of the present invention, the LAS 412 isin communication with the GMLC 414 through an M1 interface. The GMLC 414is ultimately in communication with serving nodes (MSC/SGSN/SMLC) 416.

During operation, an emergency INVITE request 403 is sent from the UE402 to the P-CSCF 404. The P-CSCF 404 detects that the user isinitiating an emergency call and forwards the emergency INVITE request405 to a S-CSCF 406 in the same network. The P-CSCF 404 and the S-CSCF406 will detect the user initiating an emergency call. There are avariety of method for doing this for example, the user may initiate a“special” INVITE message e.g. a SOS INVITE request or an INVITE with anew SIP Emergency header. In the first case, the CSCF on receipt of anSOS INVITE detects it is an emergency request. In the latter case, theCSCF will need to look in all INVITE requests for the Emergency header.It should be appreciated that a variety of alternative methods may beimplemented and still remain within the scope of the present invention.

The S-CSCF 406 detects this is an emergency call and forwards theemergency INVITE request 418 to the LAS 412. A request for routinginformation 420 is sent from the LAS 412 to a GMLC 414 in the samenetwork. The GMLC 414 sends an acknowledgement 426 to the LAS 412 withrouting information and possibly the location information, if this canbe obtained. The routing information enables the EC 408 to access theGMLC 414 in order to request the UE's 402 location information at alater time. The LAS 412 communicates an INVITE message 424 including therouting information and possibly the location information back to theS-CSCF 406. The S-CSCF 406 then communicates an INVITE message 407 tothe EC 408. If the INVITE message does not contain the locationinformation, then the EC 408 may then send a location request 428 to theGMLC 414.

At any time after the GMLC 414 receives a request for routinginformation 420, the GMLC 414 sends a Location Service (LCS) MobileTerminal Location Request (MT-LR) 422 to the server nodes 416. Theserver nodes 416 communicate a response to the GMLC 414 (as shown by thetwo-directional arrow 422).

FIG. 5 displays a message flow diagram depicting a method of acquiringlocation information after session initiation. The message flow diagramof FIG. 5 depicts the message flow between S-CSCF 500, LAS 502, GMLC 504and EC 506. During operation, The S-CSCF 500 sends a SIP INVITE request510 to the LAS 502. The LAS 502 sends a request for routing information512 to a pre-configured GMLC 504 in the same network 508. In oneembodiment, the request for routing information 512 includes the type oflocation (e.g. current location), the UE's public identity and requiredQoS (e.g. accuracy, response time).

The GMLC 504 sends a request for routing information acknowledgement514, which includes routing information that will enable the EC 506 torequest UE's (not shown in FIG. 5) location information at a later time(e.g. a routing key) and may include the UE location (ifalready/previously obtained). At any time after the request for routinginformation 512 is received, the GMLC 504 initiates the MobileTerminating Location Request (MT-LR) procedures 516 as described in 3GPPTS 23.271 V6.7.0 (2004-03) to obtain the UE's location. The LAS 502includes the routing information and possibly the location informationprovided in the request for routing information acknowledgement 514 in aSIP INVITE request 518 to the S-CSCF 500. The EC 506 requests locationinformation 520 from the GMLC 504 upon receipt of the SIP INVITE thatincludes the routing information. A variety of packet formats andmessages may be used to implement the foregoing methods. For example,the Internet Protocol or the GSM MAP protocol may be used.

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the invention is not limited thereto. Those havingordinary skill in the art and access to the teachings provided hereinwill recognize additional modifications, applications, and embodimentswithin the scope thereof and additional fields in which the presentinvention would be of significant utility.

It is, therefore, intended by the appended claims to cover any and allsuch applications, modifications, and embodiments within the scope ofthe present invention.

1. A method of obtaining location information for emergency servicesduring session initiation between mobile user equipment (UE) and anemergency center, the method comprising: receiving at a locationapplication server (LAS) a first request message from a call sessioncontrol function (CSCF) server in response to the CSCF server receivingan emergency request message from user equipment (UE); communicating alocation request from the LAS to a mobile location center in response toreceiving the first request message, the location request operable forinitiating a mobile terminal location request (MT-LR) procedure withinthe mobile location center; receiving a location response at the LASfrom the mobile location center in response to communicating thelocation request to the mobile location center, the location responsecomprising location information of the UE; and communicating a secondrequest message to the CSCF server in response to receiving the locationresponse, the second request message including the location informationof the UE.
 2. A method of obtaining location information as set forth inclaim 1, further comprising: receiving the emergency request messagefrom the UE at a proxy-CSCF (P-CSCF) server; and forwarding theemergency request message as the first request message from the P-CSCFserver to the CSCF server, the CSCF server comprising a server-CSCF(S-CSCF) server.
 3. A method of obtaining location information as setforth in claim 2, wherein the first request message is a SessionInitiation Protocol INVITE request message and the second requestmessage is a Session Initiation Protocol INVITE request message.
 4. Amethod of obtaining location information as set forth in claim 1,further comprising: receiving the emergency request message from the UEat a proxy-CSCF (P-CSCF) sever; and generating at the P-CSCF server thefirst request message and sending the first request message from theP-CSCF server to the CSCF server, the CSCF comprising a server-CSCF(S-CSCF) server.
 5. A method of obtaining location information as setforth in claim 1, wherein the first request message, is a SessionInitiation Protocol INVITE request message and the second requestmessage is a Session Initiation Protocol INVITE request message.
 6. Amethod of obtaining location information as set forth in claim 1,further comprising: obtaining the location information of UE using theMT-LR procedure within the mobile location center.
 7. A communicationsystem comprising: a call session control function for receiving anemergency request message from user equipment (UE) and, in responsethereto, generating a first request message; a location applicationserver communicatively coupled to the CSCF server for receiving thefirst request message and generating a location request; a gatewayserver communicatively coupled to the location application server forreceiving the location request and implementing a mobile terminallocation request (MT-LR) procedure to obtain location information of theUE and for generating an acknowledgement response to the locationapplication server, the acknowledgement response comprising the obtainedlocation information of the UE; and wherein the location applicationserver is operable for receiving the acknowledgement response and forcommunicating a second request message to the CSCF server, the secondrequest message including the obtained location information of the UE.8. A communication system as set forth in claim 7, wherein the CSCFserver comprises a proxy-CSCF (P-CSCF) server and a server-CSCF (S-CSCF)server, and wherein the emergency request message is received at theP-CSCF server a one of; forwarded to the S-CSCF server as the firstrequest message or terminated with the S-CSCF server generating thefirst request message in response to receiving the emergency requestmessage.
 9. A communication system as set forth in claim 7, wherein thefirst request message is a Session Initiation Protocol INVITE requestmessage and the second request message is a Session Initiation ProtocolINVITE request message.
 10. A method of obtaining location informationfor emergency services after session initiation between mobile userequipment (UE) and an emergency center, the method comprising: receivingat a location application server (LAS) a first request message from acall session control function (CSCF) server in response to the CSCFserver receiving an emergency request message from user equipment (UE);communicating by the LAS to a mobile location center a request forrouting information in response to receiving the first request message;receiving at the LAS from the mobile location center a routinginformation acknowledgement in response to communicating the request forrouting information to the mobile location center, the routinginformation acknowledgement comprising routing information associatedwith the UE enabling a request for location information of the UE;communicating a second request message to the CSCF server in response toreceiving the request for routing information acknowledgement, thesecond request message including the routing information associated withthe UE; communicating from the CSCF server the routing information to anemergency center; and after receiving the routines information,requesting, by the emergency center, location information of the UE fromthe mobile location center.
 11. A method of obtaining locationinformation as set forth in claim 10 further comprising: receiving theemergency request message from the UE at a proxy-CSCF (P-CSCF) server;and generating at the P-CSCF server the first request message andsending the first request message from the P-CSCF server to the CSCFserver, the CSCF server comprising a server-CSCF (S-CSCF) server.
 12. Amethod of obtaining location information as set forth in claim 11,wherein the first request message is a Session Initiation ProtocolINVITE request message and the second request message is a SessionInitiation Protocol INVITE request message.
 13. A method of obtaininglocation information as set forth in claim 10, wherein the first requestmessage is a Session Initiation Protocol INVITE request message and thesecond request message is a Session Initiation Protocol INVITE requestmessage.
 14. A method of obtaining location information as set forth inclaim 10, further comprising: obtaining the location information of theUE using a mobile terminal location request (MT-LR) procedure within themobile location center.